Boris Johnson has continued to make his presence felt at the 2012 Olympic Games – on this latest occasion he was left dangling 20ft in the air after getting stuck while taking part in a zip-wire act.

For those who thought they had been given a break from the mayor of London's voice after the ditching of his transport message to tube and bus users, they only needed to look up to see the unmistakable figure of Johnson hanging wistfully in the air clutching a union flag in each hand.

He took to the zip-wire in Victoria Park, east London, close to the Olympic Park, with safety helmet firmly on after Team GB's first gold medal victory. But after a promising start gliding along happily waving his flags, he lost momentum and came to a halt, dangling over a crowd of people, for a long and somewhat awkward moment.

Johnson, always game, flashed his ankles as the safety harness pulled up the trousers of his smart suit, to the evident discomfort of the London mayor. As onlookers snapped photos on their mobile phones, he tried humorous small talk before calling out in mock despair: "Get me a ladder!" Once taken safely to the end of the ride and back on terra firma, the mayor said he thoroughly recommended it and mused that someone may have forgotten to take the brake off.

After the incident, it was left to his spokesperson to admit that, were Olympic judges looking, the mayor would not be marked out as a winner. The best they could say is that he "survived" it.

"Clearly the judges are likely to mark him down for artistic interpretation and, unlike Team GB, he won't be bagging any gold medals today but he remains unbowed," said the spokesperson.

Boris Johnson asked onlookers if anyone had a rope to help get him down. Photograph: Public Domian

If overseas visitors to London had not heard of the colourful mayor before landing in London, they certainly will have by the time they leave.

David Cameron joked later that only Johnson could get away so well with getting stuck on a wire.

The PM said: "If any other politician anywhere in the world was stuck on a zip-wire it would be a disaster. For Boris, it's an absolute triumph."

At a surprise appearance at the beach volleyball in Horse Guards Parade on Monday, with 15,000 spectators present, Johnson started his own brand of the Mexican wave and got people to their feet.

With more than a week and half to go, it remains to be seen where he will pop up and precisely what he will do.

Some may have sympathy with the mayor of Rio, Eduardo Paes, who recently confided to the Independent that he was scared Johnson would "do something crazy when he hands over the flag". "He's crazy," said Paes, whose city will host the 2016 Olympic Games.

Johnson's response the same day probably did little to reassure Paes. "I want to reassure my friend Eduardo that there is no chance of me hanging on to the Olympic flag at the closing ceremony", joked Johnson, before adding mischievously "As protocol demands I will be handing it over to Eduardo — probably."